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'Red Tide' advances on Chiloé Island

12.03.2002 07:00 Chile - Algal blooms

'Red Tide' advances on Chiloé Island

Puerto Montt, Chile: The 'Red Tide' of algal blooms is reaching further and further north on the Island of Chiloé in Southern Chile. Its toxic effects are threatening the main source of income for a large part of the island's population, who earn their living from cultivating and fishing for seafood.

A large proportion of Chile's salmon farms are found in the Chiloé area. But this 'Red Tide' has not affected fish. Even though the advance of toxic marine plankton has been a serious problem for shellfish fishermen and mussel farmers, it hasn't been a problem for salmon farmers.

However, the spread of the Red Tide has caused a real catastrophe for the island, especially in the southernmost town of Quellón. According to information published by the regional newspaper El Llanquihue, Quellón was in fact the city that grew most in the southern province (Region 10) during the 1990's. But all that may now change drastically.

Ban extended
The change is due to the fact that the regional Health Service recently announced it would extend the prohibition on catching and trading bivalve products, in the entire region south of the huge Island of Chiloé. The ban was imposed because the waters are contaminated by toxic algal blooms.

The decision has been devastating for the community of Quellón, since close to 80% of the population is dedicated to the catching and trading of seafood products. In addition, the town is the principal port for unloading products coming from places further south.

The Mayor of Quellón, Iván Haro Uribe, told the newspaper that he never imagined the tremendous social and economic impact that the health measure would cause on his community, much less the increase in vagrancy and alcoholism, mainly among those who work directly with unloading products at the fishermen's wharf. And he didn't foresee even the type of measures that they will have to adopt in order to keep delinquency levels - which are already high - under control.

'Catastrophe'
For the mayor: "the repercussions will be tremendous. There were thousands of tonnes of seafood products going out, not only for domestic consumption, but also for export abroad. There are hundreds of businessmen who have put everything into this, and now they can't even take out enough seafood for personal consumption. It's truly a catastrophe."

Mussel farms in Quellón had been stretched out in a line (with white buoys marking the line), for a project started by the Austral University of Chile, supplying spat to southern Chile. Spat from here was given preference for community use, but extraction was prohibited at the end of January for the better part of Quellón.

Taking responsibility
The reasons the Mayor gives for the spread of the 'Red Tide' are the environmental conditions favourable for growth of the dinoflagellate, or phytoflagellate, which produces the toxin. But he also attributes blame to the very same fishermen, specifically those harvesting shellfish who put them in holding pools, since they may have brought shellfish from a contaminated area and introduced them to waters that had once been "clean" or disease-free.

Haro has always maintained that checks and controls are not done on boats and ships coming up from the more southern province, Region 11 to Region 10.

'Red Tides' in Region 11 have always been a problem, and in fact there are many places where extraction of shellfish is prohibited because of the danger of contamination with the toxins.

For that reason, according to the mayor of Quellón, the public coastal authority or the National Fisheries Service should have been more strict and rigorous in checking ships coming from the Southern region.

Impossible to stop
Doctor Ramón Andrade of the Environmental Programs Department for Castro [a town of Chiloé island], which is in charge of the Red Tide Laboratory, assured the newspaper that "there are no tools for saving Region 10 from the Red Tide, because it's a natural phenomenon. We can't influence the weather conditions: the temperature, lighting, rainfall, and nutrients in the sea bottom." Those factors that can unleash the explosive growth of the toxic marine plankton, producing a Red Tide.

Andrade explained that samples taken near the city of Quellón came out positive, including the sites of the majority of mollusc hatcheries and sea farms, and other places where mussels are artificially bred.

Paula Carvajal, IntraFish